This is one of the key questions facing educational technology in the next few years. Of course platform developers (Apple, Google, Facebook) would like you to build apps, for several reasons: it's specific to their technology, it can create a better experience, they can control distribution (in some cases), and they can get a cut of app purchases or in-app purchases. But to reach the full audience, it means content providers are looking and creating multiple versions. Why not just write a responsive web application? I wish Joshua Kim tried answering some questions rather than just asking them.